The field of the invention pertains to liquid cooled internal combustion engines having radiators and fans to force air through the radiators. In particular, the invention pertains to engines that are subjected to dirt and debris in the fan air stream. Applications of such engines to commercial lawn mowers and street sweepers result in significant quantities of dirt and debris blown by the radiator fan into the radiator. Within a relatively short period of use the cooling capacity of the radiator can be significantly impaired by dirt laden and clogged air passages through the radiator.
Commercial lawn mowers and street sweepers are frequently used in very hot and dry weather. Therefore, the cooling capacity of the radiator is frequently used dose to the design limit. Significant amounts of dirt and debris trapped in the radiator can cause engine overheating with loss of power and a substantially shortened engine life. Dirt and debris laden air may also cause decreased radiator cooling capacity in certain industrial processing applications and open pit mining applications of the engines whether stationary or on specialized vehicles.
Stationary grillwork and screening has been used to surround and protect radiators from flying debris. However, such screening does not inhibit dust from collecting in radiator passages. In some applications shrouds have been used with grillwork to control the air stream flow path. Such shrouds reduce easy access for repair or servicing. In other applications extensive duct work has been used to raise the inlet to the fan well above most of the debris floating in the air. Such approaches are considerably expensive or otherwise impractical for many applications.
Some air cooled internal combustion engines have been equipped with a rotating dirt and debris screen mounted on the engine crank shaft adjacent the flywheel, fan and magneto, alternator or dynamo combination. In such applications, the grillwork and shrouding of the engine remains necessary for safety reasons and to properly direct airflow about the engine cooling fins.